Pumice, a type of volcanic rock, is so porous that it floats on water, as shown in the picture below.
Now researchers from Oxford University and the University of Western Australia are suggesting that life on Earth could have formed on floating rafts of pumice.
The researchers argue that pumice has a unique set of properties which would have made it an ideal habitat for the earliest organisms that emerged on Earth over 3.5 billion years ago.
‘Not only does pumice float as rafts but it has the highest surface-area-to-volume ratio of any type of rock, is exposed to a variety of conditions, and has the remarkable ability to adsorb metals, organics and phosphates as well as hosting organic catalysts, such as zeolites,’ said Professor Martin Brasier of Oxford University’s Department of Earth Sciences who led the work with David Wacey of the University of Western Australia. ‘Taken together these properties suggest that it could have made an ideal ‘floating laboratory’ for the development of the earliest micro-organisms.’
Floating pumice could have been exposed to lightning, oily residue and metals from hydrothermal vents, and ultraviolet light. All of these conditions have the potential to generate the kinds of chemical reactions that scientists hypothesize created the first living cells.
The scientists plan to test their hypothesis by subjecting pumice rocks with cycles of heat and radiation to see if the process creates molecules associated with life. They also plan to examine the early fossil record for evidence of fossils in pumice.
If scientists can determine how life on Earth began, they’ll be better prepared to search for evidence of life on other planets.
Learn about the search for extraterrestrial life in the High-Adventure Science space investigation.